1997 75HP 2 Stroke Max RPM

[starflt1701]

Have a 16' Sea Ray runabout with a '97 Merc 2 stroke 75 HP engine. Just had the carbs rebuilt on the outboard. Planes off fine. Cruises just fine. Have always been able to hit 5200 RPM and 42-43 MPH top end with this boat/motor. Since rebuild, can't get above 5000 RPM or 40 MPH. Prop is the same. Changed spark plugs. No difference. Checked compression. All 3 cyls right at 130 PSI +/- 1. While at WOT bumped the enricher a couple times to see if a fuel restriction. Each time engine bogged very momentarily, so doesn't seem to be fuel flow related.

I realize it's not a major difference, but any thoughts on why I can't hit 5200 RPM any more?

Thanks.

 

[1nebel0]

Re: 1997 75HP 2 Stroke Max RPM

Lync and sync mandatory....are they all opening to full throttle..most likely your problem...let us know...5200 is on the light side... motor is rated to 5500 and I always like closer than farther from max rpm to insure not lugging motor...If you load the boat you won't get 5200 and you will be lugging...my 02

 

[starflt1701]

Re: 1997 75HP 2 Stroke Max RPM

Thanks for your reply. Hadn't thought about that I guess because I would have expected the shop who did the rebuilds to perform the lync and sync. But worth checking. I'm not a mechanic but am pretty handy. Is this something I should be able to do myself or is it complicated/requiring special tools?